BRPI0722121B1 - TIRE - Google Patents

Abstract

A tire comprising at least one structural element including a crosslinked elastomeric material obtained by crosslinking a crosslinkable elastomeric composition comprising: (a) 100 phr of at least one elastomeric polymer; (b) from about 0.1 phr to about 120 phr, preferably from about 20 phr to about 90 phr of at least one reinforcing filler; (c) from about 1 phr to about 80 phr, preferably from about 2 phr to about 60 phr of glass flakes having an average thickness equal to or lower than 5.0 µm and an average aspect ratio higher than 1. Preferably, said structural element is selected from: bead filler, tread band, tread underlayer, antiabrasive layers, sidewalls, or sidewall inserts.

Description

Field of invention

The present invention relates generally to a tire and a crosslinkable elastomeric composition composed of glass flakes.

More particularly, the present invention relates to a tire, including at least one structural element obtained by crosslinking a crosslinkable elastomeric composition composed of glass flakes having a specific thickness and a specific aspect ratio.

In addition, the present invention also relates to a crosslinkable elastomeric composition consisting of glass flakes having a specific thickness and a specific aspect ratio, as well as to a crosslinked manufactured article obtained by crosslinking said crosslinkable elastomeric composition.

Background of the invention

In the rubber industry, especially the tire-making industry, it is known practice to use additives with crosslinkable elastomeric compositions to improve the mechanical properties of the finished product (i.e., the cross-linked manufactured article).

For example, the hardness of elastomeric compositions can be increased by increasing the crosslink density of these compositions, using a large amount of sulfur; or using a large amount of carbon black, or a very fine and structured carbon black. However, the above ways of increasing the hardness may have several disadvantages.

For example, it is known that the use of a large amount of sulfur may cause a notable reversal phenomenon, which results in a change in the performance of the tire during use. On the other hand, it is known that carbon black provides the reticulated manufactured product with pronounced hysteresis properties, that is, an increase in the heat dissipated under dynamic conditions, which results in an increase in the rolling resistance of the tire and consumption of fuel. In addition, a large amount of carbon black causes an increase in the viscosity of the elastomeric composition and, as a result, has a negative impact on the processing and extrusion capacity of the crosslinkable elastomeric composition.

To overcome the disadvantages caused by the use of carbon black, so-called "white" reinforcement charges, usually silica, are usually used in the total or partial replacement of carbon black. However, although the use of said reinforcement loads leads to good tensile strength, it also includes a number of disadvantages related essentially to the poor affinity of these loads with respect to the elastomeric polymers commonly used in tire production. In particular, in order to obtain a good degree of dispersion of silica in elastomeric polymers, it is necessary to subject the elastomeric compositions to a prolonged action of thermomechanical mixing. To increase the affinity of silica with elastomeric polymers, it is necessary to use suitable copulating agents, such as sulfur-containing organo-silane products. However, the need to use such copulating agents places a limitation on the maximum temperature that could be reached during mixing and thermomechanical processing operations of the composition, to avoid the penalty of irreversible thermal degradation of the copulating agent.

In addition, the processing capacity of such crosslinkable elastomeric compositions consisting of reinforcing fillers, such as carbon black and / or silica, would require high temperatures, but this means a reduction in productivity, an excessive consumption of energy, and an increased risk of defect formation due to premature partial cure ("firing phenomenon").

Usually, an attempt has been made to solve the problems mentioned above by adding fatty acid salts with sodium or zinc (soaps), or by adding lubricants or oils, which could reduce viscosity and increase the flow capacity. However, the use of such ingredients involves the problem of a reduction in the tensile modulus and the hardness of the resulting cross-linked elastomeric composition.

Recent approaches to improve the processing capacity of crosslinkable elastomeric compositions, made of silica, have been directed towards reducing or replacing the use of silica copulating agents, through the use of silica dispersion aids, such as protection of monofunctional silica (for example, hydrophobic silica agents that react chemically with the silanol groups on the surface on the silica particles, but are not reactive with the elastomeric polymer) and agents that physically protect the silanol groups, to prevent re-agglomeration ( flocculation) of the silica particles after the formation of the compounds. Silica processing aids useful for such purposes are described, for example, in United States patent US 6,512,035 which discloses the use of one or more monofunctional alkyl tin compounds, in United States patent US 6,608,145 which discloses the use of silica dispersion aids, such as alkyl alkoxysilanes, glycols (eg, diethylene glycol, or polyethylene glycol), hydrogenated and non-hydrogenated C5 and C6 fatty acid esters (eg, sorbitan oleates), derivatives polyoxyethylene fatty acid esters, and fillers, such as mica, talc, urea, clay, sodium sulfate, or in the United States patent US 7,041,745 which presents the use of polar additives, such as polyvinyl acetate (PVA ). The use of glass particles, of any shape, has never been mentioned or suggested to solve the problems mentioned above.

United States patent US 7,122,090 shows an excellent tire in performance on ice and snow having a tread composed of a rubber plate obtained from a rubber composition that contains 2 to 50 parts by weight of short fibers or similar material to plates, based on 100 parts by weight of diene rubber, where said short fiber material has an average fiber diameter of 1 to 100 pm and an average length of 0.1 to 5 mm, and said similar material the plate has an average thickness of 1 to 90 pm and an average length of 0.1 to 5 mm. The short fiber is preferably an organic and / or inorganic short fiber. An example of organic short fiber is a polyester fiber. Examples of short inorganic fibers are glass fibers, carbon fibers, metallic fibers (tungsten, iron, copper, platinum, stainless steel) and potassium titanate fibers. Examples of the plate-like material are aluminum hairs, potassium titanate hairs, aluminum borate hairs, titanate oxide type hairs and zinc oxide hairs.

United States patent US 6,770,700 discloses crosslinkable compositions based on organo-silicon compounds and moldings produced from them still containing glass flakes, having a thickness of 0.1 to 20 pm, a length of 1 to 5000 pm and a width of 1 to 5000 pm, and a ratio between width or length and thickness in the range of 10: 1 to 2000: 1.

Summary of the invention

The problem of improving the processing capacity of crosslinkable elastomeric compositions made up of reinforcement loads was faced, without negatively affecting or even improving the mechanical properties of the manufactured reticulated products obtained, especially of the tires obtained.

It was found that the problem mentioned above can be overcome by adding to the crosslinkable elastomeric compositions that can be used advantageously in the production of crosslinked manufactured products, especially in the manufacture of tires, by adding in the crosslinkable elastomeric compositions glass flakes having both a thickness specific mean as a specific aspect ratio.

Especially, the crosslinkable elastomeric compositions made up of such glass flakes show low viscosity and good flow capacity, and consequently, good processing and extrusion capacity. In addition, the reticulated manufactured articles obtained maintained the mechanical characteristics unchanged or even improved.

In addition, it was also found that the crosslinked elastomeric compositions obtained, especially in the case of elastomeric compositions that could be used advantageously in the manufacture of a tire tread, show a reduced variation in the dynamic elastic modulus (E ') when the temperature increases (specifically, a reduced "thermoplastic behavior" of the crosslinked elastomeric compositions, which, in consequence, are capable of maintaining elastic performance qualities essentially constant over a wide temperature range, which is of fundamental importance when using the crosslinkable elastomeric compositions in the manufacture of tires).

Additionally, it was also found that the crosslinked elastomeric compositions obtained show an improved isotropic reinforcement both in the direction of the calendering and in the orthogonal direction thereto. A pneumatic tire composed of a structural element, such as a bead load, a tread, a lower layer of the band, anti-abrasive layers, sides, or inserts in the sides, manufactured with the reticulated elastomeric compositions of the current invention, in Consequently, they show an improved resistance against the lateral forces applied to the tire during rolling, especially during bending.

Thus, in a first aspect, the current invention relates to a tire consisting of at least one structural element, including a crosslinked elastomeric material obtained by crosslinking a crosslinkable elastomeric composition consisting of: (a) 100 ppc of at least one elastomeric polymer; (b) about 0.1 ppc to about 120 ppc, preferably about 20 ppc to about 90 ppc with at least one reinforcement charge; (c) about 1 to about 80 ppc, preferably about 2 ppc to about 60 ppc of glass flakes having an average thickness of 5.0 pm or less, and an average aspect ratio greater than 1.

According to a preferred embodiment, said tire is composed of: - a carcass structure with a substantially toroidal shape, having opposite side edges associated with the respective right and left tread structures; - a belt structure applied in a radially external position with respect to said carcass structure; - a tread applied in a radially external position with respect to said belt structure; - a pair of sides applied laterally on opposite sides with respect to said carcass structure; where said structural element is at least one of said tread, or said pair of sides.

Preferably, said bead structures are defined by the respective folds of the carcass and constitute at least one core of beads and at least one bead load, said bead load being said structural element.

Preferably, said tire may also consist of: - a lower layer of the tread applied in a radially internal position with respect to said tread; and optionally, a pair of side inserts extending radially from each of said bead structures to the corresponding side edge of said tread; and optionally, a pair of anti-abrasive layers placed in an axially external position with respect to said fold of the housing; wherein said structural element is at least one of said tread lower layer, or said pair of side inserts, or said pair of anti-abrasive layers.

In a second aspect, the current invention relates to a crosslinkable elastomeric composition consisting of: (a) 100 ppc of at least one elastomeric polymer; (b) about 0.1 ppc to about 60 and 20 ppc, preferably about 20 ppc to about 90 ppc with at least one reinforcement charge; and (c) about 1 ppc to about 80 ppc, preferably about 2 ppc to about 60 ppc of glass flakes having an average thickness of 5.0 pm or less, and a greater average aspect ratio than 1.

For the purposes of the current description and the claims that follow, the term "aspect ratio" means the relationship between the diameter and thickness of a glass flake, and the term "average aspect ratio" means the relationship between the average diameter and the average thickness of a representative sample of glass flakes; the term "diameter" of a glass flake means the diameter of a circle having an area equivalent to the projected area of the glass flake as seen in a photomicrograph.

For the purposes of the current description and the claims that follow, the term "ppc" means parts by weight of a particular component of the crosslinkable elastomeric composition per 100 parts by weight of the elastomeric polymer.

The current invention, at least in one of the aspects mentioned above, may show one or more of the preferred features described here later.

According to a preferred embodiment, said glass flakes (c) may be constituted of any desired type of glass, preferably inorganic glass. Examples of glass types of which the glass flakes are composed, include industrial glass, quartz glass, borosilicate glass, flat glass, pressed glass, bottle glass, table glass, mirror glass and ceramic glasses, special preference is given to industrial glass, flat glass, borosilicate glass, or ceramic glasses, or mixtures thereof, especially flat glass, industrial glass, or borosilicate glass.

The glass flakes (c) used in accordance with the current invention may not be treated or may be treated on the surface with functional silanes. Surface treated glass flakes are especially preferred.

The use of glass flakes treated on the surface may allow to obtain a more homogeneous dispersion of them in the elastomeric polymer.

Specific examples of functional silanes that could be used advantageously for the surface treatment of glass flakes include: aminopropyltrialoxysilanes, such as aminopropyltriethoxysilanes, aminoethylaminopropyltrialoxysilanes; vinyltrialoxysilanes, such as vinyltrimethoxy silanes, vinyltriacetoxy silane; glycidoxypropyltrialoxy silanes, such as glycidoxypropyltrimethoxy silane; methacryloxypropyl-trialkoxysilanes, such as methacryloxypropyltrimethoxysilanes; polysulfurized alkoxysilanes, such as di-, tri-, and bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl); or mixtures thereof. Preferably bis (3-triethoxysilyl) tetrasulfide, short for TESPT, or bis (triethoxysilylpropyl) disulfide, short for TESPD.

Alternatively, the glass flakes (c) used in accordance with the current invention may have been coated with metallic vapor, or provided with a coating on the surface of a purely organic or purely inorganic nature.

According to a preferred embodiment, said glass flakes (c) have an average thickness of about 0.01 pm to about 5.0 pm, preferably about 0.05 pm to about 2.0 pm , more preferably, about 0.2 pm to about 1.0 pm.

According to another preferred embodiment, said glass flakes (c) have an average diameter of about 0.1 pm to about 3000 pm, more preferably, about 1 pm to about 1500 pm, more preferably , about 1 pm to about 500 pm.

According to another preferred embodiment, said glass flakes (c) have an average aspect ratio greater than 2, and more preferably, greater than 10.

According to another preferred embodiment, said average aspect ratio is in the range of about 10: 1 to about 1000: 1, more preferably, about 20: 1 to about 900: 1, and most preferably , about 50: 1 to about 800: 1.

The glass flakes (c) reported above may have very different geometries, for example, in the form of flat platelets, with grease, rolled or twisted, but preferably, they are flat.

The glass flakes (c) reported above are commercially available, and may be purchased, for example, from Glass Flake Ltd., Leeds, UK. Examples of commercial products that could be used advantageously according to the current invention are: micronized, ground or unground ECR glass flakes GF50nm, GFlOOnm, GF350nm, GF500nm, GF750nm, GF100, GF200, GF100M, GF200M, GF001 and GF002.

As a consequence of the production, the glass flakes may be in the form of a mixture with other glass particles, such as powders or fibers. However, the projected area of said glass flakes represents at least about 50%, preferably at least about 70%, and most preferably, at least about 80% of the total projected area of all glass particles. contained in the mixture.

The crosslinkable elastomeric composition according to the current invention is preferably composed of glass flakes (c) in amounts of about 1 ppc to about 80 ppc, more preferably, about 2 ppc to about 60 ppc. Crosslinkable elastomeric compositions having a glass flake content of about 3 ppc to about 20 ppc may be especially advantageous.

According to a preferred embodiment, said at least one elastomeric polymer (a) can be selected, for example, from diene elastomeric polymers (ai) which are commonly used in sulfur crosslinkable elastomeric compositions, which are especially suitable for production tires, that is, polymers or elastomeric copolymers with an unsaturated chain having a glass transition temperature (Tg) generally below about 20 ° C, preferably in the range of about 0 ° C to about- 110 ° C. These polymers or copolymers may be of natural origin or may be obtained by solution polymerization, emulsion polymerization or gas phase polymerization of one or more conjugated diolefins, optionally mixed with at least one comonomer selected from monovinylarenes and / or polar comonomers. Preferably, the polymers or copolymers obtained contain said at least one comonomer selected from monovinylarenes and / or polar comonomers in an amount not greater than about 60% by weight.

Conjugated diolefins generally contain 4 to 12, preferably 4 to 8 carbon atoms, and can be selected, for example, from: 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1 , 3-pentadiene, 1,3-hexadiene, 3-butyl-1,3-octadiene, 2-phenyl-1,3-butadiene, or mixtures thereof. 1,3-butadiene or isoprene are especially preferred.

Monovinylenes which could optionally be used as comonomers, generally contain 8 to 20, preferably 8 to 12 carbon atoms, and can be selected, for example, from: styrene; 1- vinylnaphthalene; 2-vinylnaphthalene; various styrene alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl derivatives, such as α-methylstyrene, 3-methylstyrene, 4-propylstyrene, 4-cyclohexyl-styrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4- p-tolylstyrene, 4- (4-phenylbutyl) styrene, or mixtures thereof. Especially preferred is styrene.

Polar comonomers that could optionally be used, may be selected, for example, from: vinyl-pyridine, vinylquinoline, acrylic acid and alkylacrylic acid esters, nitriles, or mixtures thereof, such as methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, acrylonitrile, or mixtures thereof.

Preferably, said elastomeric polymer of diene (ai) may be selected, for example, from: cis-1,4-polyisoprene (natural or synthetic, preferably natural rubber), 3,4-polyisoprene, polybutadiene (especially, polybutadiene with a high content of 1,4-cis), optionally halogenated isoprene / isobutene copolymers, copolymers of 1,3-butadiene / acrylonitrile, styrene / 1,3-butadiene copolymers, styrene / isoprene / l, 3 copolymers -butadiene, styrene / 1,3-butadiene / acrylonitrile copolymers, or mixtures thereof.

Alternatively, said at least one elastomeric polymer (a2) may be selected, for example, from elastomeric polymers (a2) of one or more mono-olefins with an olefinic comonomer or derivatives thereof. Mono-olefins may be selected, for example, from: ethylene and α-olefins generally containing 3 to 12 carbon atoms, such as, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, or mixtures thereof. The following are preferred: copolymers between ethylene and an ocoolefin, optionally with a diene; isobutene homopolymers or copolymers thereof with small amounts of a diene, which are optionally at least partially halogenated. The optionally present diene generally contains 4 to 20 carbon atoms, and is preferably selected from: 1,3-butadiene, isoprene, 1,4-hexadiene, 1,4-cyclohexadiene, 5-ethylidene-2-norbomene, 5- methylene-2-norbomene, vinylnorbomene, or mixtures thereof. Among these, the following are especially preferred: ethylene / propylene copolymers (EPR) or ethylene / propylene / diene copolymers (EPDM); polyisobutene; and butyl rubbers; halobutyl rubbers, especially chlorobutyl or bromobutyl rubbers; or mixtures thereof.

Mixtures of the diene elastomeric polymers (aj) mentioned above with the elastomeric polymers (a?) Mentioned above could also be used.

The elastomeric polymers reported above (a) may optionally be functionalized by reaction with suitable terminating agents or copulating agents. Especially, elastomeric diene polymers (aj obtained by anionic polymerization in the presence of an organometallic initiator (especially, with the organolithium initiator) may be functionalized by reacting the residual organometallic groups derived from the initiator with suitable terminating agents or copulation agents such as such as, for example, imines, carbodiimides, alkyl tin, halides, substituted benzophenones, alkoxysilanes or aryloxysilanes (see, for example, European patent EP 451,604, or United States patents US 4,742,124 or US 4,550,142).

The elastomeric polymers reported above (a) may optionally include at least one functional group which may be selected, for example, from: carboxylic groups, carboxylate groups, anhydride groups, ester groups, epoxy groups, or mixtures thereof.

According to a preferred embodiment, said at least one reinforcement load (b) can be selected from those commonly used for cross-linked manufactured products, especially for tires, such as carbon black, silica, alumina, aluminum silicates, calcium carbonate, kaolin, or mixtures thereof. Carbon black, silica or a mixture thereof is particularly preferred.

According to a preferred embodiment, said carbon black reinforcement charge can be selected from those having a surface area of not less than 20 m2 / g (determined by CTAB absorption as described in the ISO 6810: 1995 standard).

According to a preferred embodiment, said silica reinforcement filler can be selected, for example, from: progenic silica, precipitated amorphous silica, wet silica (hydrated silicic acid), dry silica, anhydrous silicic acid, smoked silica, silicate of calcium, or mixtures thereof. Other suitable fillers include aluminum silicate, magnesium silicate or mixtures thereof. Among these, treated silicas precipitated by an amorphous wet process are preferred. These silicas are called so because they are produced by a chemical reaction in water, from which they are precipitated as ultrafine spherical particles. These primary particles are strongly associated in aggregates, which in turn are combined less strongly in agglomerates. The BET surface area, measured according to the ISO 5794-1: 2005 standard, produces the best measurement of the reinforcement character of different silicas.

Such silica reinforcement fillers which can be used advantageously according to the current invention, preferably have a surface area of about 32 m2 / g to about 400 m2 / g, more preferably, of about 100 m2 / ga about 250 m2 / g, even more preferably about 150 m2 / g to about 220 m2 / g. The pH of said silica reinforcement fillers is generally about 5.5 to about 7.0, preferably about 5.5 to about 6.8.

Examples of silica reinforcing fillers that could be used according to the current invention that are commercially available are the products known as Hi-Sil® 190, Hi-Sil® 210, Hi-Sil® 215, Hi-Sil® 233, Hi-Sil® 243, from PPG Industries (Pittsburgh, Pa.); or products known by the name Ultrasil® VN2, Ultrasil® VN3 by Degussa; or the product known under the name Zeosil® 1165MP from Rhodia.

When a reinforcement charge composed of silica is present, the crosslinkable elastomeric composition can advantageously incorporate a silane copulating agent capable of interacting with the silica and bonding it to the elastomeric polymer during vulcanization.

Copulation agents that are preferably used are those based on silanes that could be identified, for example, by the following structural formula (I): (R2) 3Si-C1H21-X (I) where the R2 groups, which can be the same or different from each other, are selected from: alkyl, alkoxy or aryloxy groups, or halogen atoms, provided that at least one of the R2 groups is an alkoxy or aryloxy group; t is an integer from about 1 to about 6 extremes included; and X is a group selected from: nitrous, mercapto, amino, epoxide, vinyl, imide, chlorine, - (S) uC1H2i-Si- (R2) 3 or -S-COR2 in which uet are integers from about 1 to about 6 extremes included and groups R2 are defined as reported above.

Among the copulating agents that are especially preferred are bis (3-triethoxysilylpropyl) tetrasulfide or bis (3-triethoxysilylpropyl) disulfide. Said copulating agents may be used as such or as a suitable mixture with an inert filler (for example, carbon black) to facilitate their incorporation into the crosslinkable elastomeric composition.

The crosslinkable elastomeric composition reported above can be vulcanized according to known techniques, especially with sulfur-based vulcanization systems commonly used for elastomeric polymers. For this purpose, in the elastomeric composition, after one or more steps of thermomechanical processing, a sulfur-based vulcanizing agent is incorporated together with vulcanization accelerators. In the final processing step, the temperature is generally kept below 120 ° C, and preferably below 100 ° C, to avoid any undesirable pre-crosslinking phenomena.

The most advantageously used vulcanizing agent is sulfur, or sulfur-containing molecules (sulfur donors), with accelerators and activators known to those skilled in the art.

Activators that are especially effective are zinc compounds, and especially ZnO, ZnCO3, zinc salts of saturated or unsaturated fatty acids containing 8 to 18 carbon atoms, such as, for example, zinc stearate, which are preferably formed in situ elastomeric composition of ZnO and fatty acid, and also BiO, PbO, PbsO4, PbO2, or mixtures thereof.

Accelerators that are commonly used may be selected from: dithiocarbamates, guanidine, thiourea, thiazoles, sulfenamides, thioureas, amines, xanthates, or mixtures thereof.

Said cross-linkable elastomeric composition may consist of other commonly used additives selected based on the specific application for which the elastomeric composition is intended. For example, the following can be added to said crosslinkable elastomeric composition: antioxidants, anti-aging agents, plasticizers, adhesives, antiozonants (especially of the p-phenylenediamine type), waxes, modifying resins, fibers (for example, Kevlar® pulp ), or mixtures thereof.

For the purpose of further improving the processing capacity, a plasticizer generally selected from mineral oils, vegetable oils, synthetic oils, or mixtures thereof, such as aromatic oil, naphthenic oil, phthalates, may be added to said crosslinkable elastomeric composition. soybean oil or mixtures thereof. The amount of opacifier generally ranges from about 0 ppc to about 70 ppc, preferably from about 1 ppc to about 30 ppc.

The crosslinkable elastomeric composition reported above can be prepared by mixing together the elastomeric polymer, the reinforcement filler (b) and the glass flakes (c) reported above, with the other additives optionally present according to techniques known in the art. The mixing can be carried out, for example, using an open mixer of the open mill type, or an internal mixer of the type with tangential rotors (Banbury) or with interlocked rotors (Intermix), or even in continuous mixers of the Ko-Kneader type (Buss), or the type of twin screws rotating in the same direction or opposite rotations.

Alternatively, the glass flakes can be previously mixed with the elastomeric polymer to form a master batch that will later be mixed with the remaining components of the crosslinkable elastomeric composition.

The process for producing the tire according to the current invention can be carried out according to techniques using devices that are known in the art, said process including the production of a green tire, and later, the molding and vulcanization of the green tire.

Brief description of the drawings

The current invention will now be illustrated in greater detail by means of illustrative embodiments, with reference to the attached figures where: -Figure 1 is a section in section of a portion of a tire made in accordance with an embodiment of the current invention. Figure 2 is a cross-sectional view of a portion of a tire made in accordance with another embodiment of the current invention.

Detailed description of preferred achievements

With reference to figure 1, "a" indicates an axial direction and "r" indicates a radial direction. For simplicity, figure 1 shows only a portion of the tire, the remaining portion not shown being identical and placed symmetrically with respect to the radial direction "r".

The tire (100) is composed of at least one carcass layer (101), the opposite side edges of which are associated with the respective bead structures that are composed of at least one bead core (102) and at least one load accounts (104). The association between the shell layer (101) and the bead core (102) is achieved here by turning the opposite side edges of the shell layer (101) around the bead core (102) to form the so-called fold housing (101a) as shown in figure 1.

Alternatively, the conventional bead core (102) may be replaced with at least one annular insert formed from rubberized wires placed in concentric coils (not shown in figure 1) (see, for example, European patent applications EP 928,680, or EP 928,702). In this case, the carcass layer (101) is not turned upwards around said annular inserts, the copulation being produced by a second carcass layer (not shown in figure 1) applied extremly on the first.

The carcass layer (101) is usually composed of a number of reinforcement cords placed in parallel with each other, and at least partially coated with a layer of a cross-linked elastomeric composition. These reinforcement cords are usually made of textile fibers, for example, rayon, nylon or polyethylene terephthalate, or of braided steel wires, coated with a metallic alloy (for example, copper / zinc alloys, zinc / manganese, zinc / molybdenum / cobalt, and the like).

The carcass layer (101) is usually of the radial type, i.e., it incorporates the reinforcement cords placed in a direction substantially perpendicular to a circumferential direction.

The core (102) is within a bead (103) defined along an inner circumferential edge of the tire (100), with which the tire is fitted under an edge (not shown in figure 1) forming part of a wheel. vehicle. The space defined by each fold of the housing (101a) contains a bead load (104) that can be made according to the current invention.

An anti-abrasive layer (105) that can be made according to the current invention, is usually placed in an axially external position with respect to the fold of the housing (101a).

A belt structure (106) is applied along the circumference of the carcass layer (101). In the specific embodiment of figure 1, the strap structure (106) is composed of two strap strips (106a, 106b) that incorporate a number of reinforcement cords, typically metallic cords, which are parallel to each other on each strip and they are intercepted with respect to the adjacent strip, oriented to form a predetermined angle relative to a circumferential direction. On the strip of the radially outermost belt (106b), at least one zero degree reinforcement layer (106c) may optionally be applied, and is commonly known as a "0 ° belt", which generally incorporates a number of reinforcement cords, typically textile cords, placed at an angle of a few degrees in relation to a circumferential direction, usually covered with a crosslinked elastomeric composition.

A tread (109), which can be made according to the current invention, whose side edges are connected at the sides (108), is applied circumferentially in a position radially external to the structure of the belt (106). Extremely, the tread (109) has a rolling surface (109a) designed to contact the ground. Circumferential grooves that are connected by transverse slits (not shown in figure 1) to define a number of blocks of various shapes and sizes distributed over the bearing surface (109a) are usually made on these surfaces (109a), which are represented, for simplicity , in figure 1, as being smooth.

A side (108), which can be made according to the current invention, is also applied extremly on the layer of the carcass (101), this side extending in an axially external position, from the bead (103) to the end of the strap structure (106).

A tread sublayer (111), which can be made according to the current invention, can be placed between the belt structure (106) and the tread (109). As shown in figure 1, the tread sublayer (111) may be of uniform thickness. Alternatively, the tread sublayer (111) may have a variable thickness in the transverse direction. For example, the thickness may be greater near its outer edges than in a central zone. In figure 1, said tread sublayer (111) extends over a surface substantially corresponding to the development surface of said belt structure (106). Alternatively, said tread sublayer (111) extends only along at least a portion of the development of said belt structure (106), for example, on opposite side portions of said belt structure (106) (not represented in figure 1).

A layer made of crosslinked elastomeric material (110), commonly known as a "mini-side", may optionally be present in the connection area between the sides (108) and the tread (109), this mini-side is generally obtained by coextrusion with the tread and allowing an improvement of the mechanical interaction between the tread (109) and the sides (108). Alternatively, the end portion of the side (108) directly covers the lateral edge of the tread (109).

In the case of tubeless tires, a rubber layer (112) generally known as a lining, which produces the necessary impermeability to the tire's inflated air, can also be produced in an internal position in relation to the carcass layer (101).

Figure 2 shows a tire (100) having a structure as described in figure 1 (the same reference numbers have the same meanings as shown in figure 1) and are also composed of an insert in the side (113), which can be made according to with the current invention. The insert in the side (113) extends radially from the bead structure (103), said bead structure being made up of the bead core (102), the fold of the shell (101a), and the bead load (104), to the side edge of the tread (109). The insert in the side (113) is placed in an axially internal or external position with respect to the layer of the carcass: for example, as shown in Figure 2, the insert in the side (113) is placed between the carcass layer (101) and the coating (112). Alternatively, if more than one carcass layer is present, a side insert (113) is placed between two of said carcass layers (not shown in figure 2). Alternatively, a side insert (113) is placed between the carcass layer and the side (not shown in figure 2). More than one side insert may be present as shown, for example, in United States patent US 5,238,040, or in European patent application EP 943,466.

Said side insert (113) is usually used in the case of tires with prolonged mobility, such as, for example, flat racing tires.

Although the current invention has been illustrated specifically in relation to a tire, other cross-linked elastomeric articles that could be produced according to the invention may, for example, be conveyor belts, drive belts, or hoses.

The current invention will be further illustrated below by means of a number of preparation examples, which are presented for purely indicative purposes and without any limitation to this invention.

The samples in the following examples are evaluated according to the following measurement tests.

Mooney ML (l + 4) viscosities at 100 ° C were measured according to the ISO 289-1: 1994 standard, in the non-crosslinked elastomeric compositions obtained as described below.

The tensile modulus (10% modulus, 50% modulus, 100% modulus, and 300% modulus), the tensile stress, as well as the elongation at break, were measured according to the ISO 37: 2005 standard , both in the direction of the calendering and in the direction perpendicular to it, in samples of the elastomeric compositions described below vulcanized at 170 ° C for 10 minutes. The ratio of 100% of the traction module is the relationship between the 100% traction module measured along the calendering direction and the 100% traction module in the direction perpendicular to it.

The hardness in IRHD degrees (at 10 ° C, 23 ° C and 100 ° C) according to the ISO 48: 1994 standard and Shore hardness according to ISO 7619-1: 2004, were measured in samples from elastomeric compositions vulcanized at 170 ° C for 10 minutes.

The dynamic mechanical properties were measured using an Instron dynamic device in the compression-traction mode according to the following methods. A test piece of the crosslinked elastomeric composition (vulcanized at 170 ° C for 10 minutes) having a cylindrical shape (length = 25 mm; diameter = 12 mm), previously loaded by compression up to 25% longitudinal deformation with respect to the initial length , and maintained at a previously fixed temperature (10 ° C, 23 ° C, and 70 ° C) for the entire duration of the test, it was subjected to dynamic sinusoidal traction having an amplitude of more or less than 3.5% with respect to length under previous load and, with a frequency of 100 Hz. The dynamic mechanical properties are expressed in terms of values of the dynamic elastic modulus (E ') and Tan delta (loss factor). The value of Tan delta is calculated as the ratio between the viscous modulus (E ") and the elastic modulus (E '). The thermoplastic behavior is evaluated as the difference ΔE' between the dynamic elastic modulus measured at two reference temperatures selected with based on the type of elastomeric composition and / or its application on the tire.

EXAMPLE 1 Preparation of elastomeric compositions 1 to 6 (tread)

The elastomeric compositions 1 to 6 shown in table 1 were prepared as follows (the amounts of the various components are shown in ppc)

(*) comparação (A) InvençãoAll components, except sulfur and accelerators (TBBS), were mixed together in an internal mixer (model Pomini PL 1.6) for about 5 minutes (first stage). As soon as the temperature of 145 ± 5 ° C was reached, the elastomeric composition was discharged. Sulfur and accelerators (TBBS) were then added and mixing was performed in an open roller mixer (second stage).

(*) comparison (A) Invention

SBR: styrene / 1,3-butadiene copolymer prepared in emulsion having a styrene content of 23.5% by weight (Europrene® 1500- Polimeri Europa);

BR: polybutadiene (Europrene Neocis® BR40-Polimeri Europa);

NR: natural rubber (SMR GP);

Silica: Zeosil® 1165 MP (Rhodia);

TESPT: bis (3-triethoxysilylpropyl) tetrasulfide (Degussa-Hüls);

N234: carbon black

GF002: micronized glass flakes with a thickness of 2 pm and aspect ratio around 30: 1 treated with about 8% by weight of TESPD (Glass Flake Ltd);

GF350nm: ground glass flakes with a thickness of 350 nm and aspect ratio around 850: 1 treated with about 8% by weight of TGESPD (Glass Flake Ltd);

RICS: 10 pm glass fibers (Nippon Glass

Fibers); antioxidant: phenyl-p-phenylenediamine (6-PPD-Akso Nobel);

TBBS: N-tert-butyl-2-benzothiazysulfenamide (Vulkacit® NZ / EGC - Lanxess).

5 All samples were evaluated as described above and the results are summarized in Table 2 below.

TABLE 2

Samples 4 and 5 according to the current invention showed a viscosity equal to or less than that of sample 1 (set to 100) and even lower than that of sample 2 and 3, consisting of an increased amount of charge (black smoke or silica). A reduced viscosity in the non-cross-linked state means better processing capacity. The hardness is increased in all cases for both temperatures considered.

Sample 5 and even more sample 4 showed very good values of dynamic properties. The greatest reinforcement was obtained for samples 5 and 6, but the latter is much more thermoplastic (higher ΔE' value between 23 ° C and 70 ° C).

Another important advantage of the glass flakes comes from the analysis of the tensile properties measured along two perpendicular directions. Table 2 shows the values of the tensile modulus measured along two orthogonal directions in relation to each other, to evaluate the reinforcement in two dimensions. The data in Table 2, as evidenced by the value of the tensile modulus in the proportion of 100%, clearly showed that the glass flakes produce an isotropic reinforcement, even better than conventional fillers, whereas the glass fibers do not.

EXAMPLE 2 Preparation of elastomeric compositions 7 to 11 (tread)

The elastomeric compositions 7 to 11 shown in table 3 were prepared as follows (the amounts of the various components are shown in ppc).

All components, except sulfur and accelerators (DPG80 and CBS), were mixed together in an internal mixer (model Pomini PL 1.6) for about 5 minutes (first stage). As soon as the temperature reached 145 ± 5 ° C, the elastomeric composition was discharged. Sulfur and accelerators (DPG and CBS) were then added and the mixing was carried out in an open roller mixer (second stage).

(*) comparação (A) InvençãoTABLE 3

(*) comparison (A) Invention

S-SBR: styrene / 1,3-butadiene copolymer prepared in solution having a styrene content of 25% by weight and a vinyl content of 50% by weight, in relation to the total weight of the copolymer; and containing 37.5 ppc of aromatic oil (Buna® VSL 5025-1-Lanxess);

BR: polybutadiene (Europrene Neocis® BR40-Polimeri Europa);

Silica: Zeosi® 1165 MP (Rhodia);

TESPT: bis (3-triethoxysilylpropyl) tetrasulfide (Degussa-Hüls);

GF001: micronized glass flakes with thickness around 1 pm and aspect ratio around 45: 1 treated with about 8% by weight of TESPD (Glass Flake Ltd.);

GF350nm: flakes of ground glass with a thickness of about 350 nm and aspect ratio around 850: 1, treated with about 8% by weight of TESPD;

Antioxidant: phenyl-p-phenylenediamine (6-PPD-Akso Nobel);

DPG80: diphenyl guanidine (Rhenogran® DPG80-Rhein Chemie);

CBS: N-cyclohexyl-2-benzothiazil-sulfenamide (Vulkacit® CZ / C-

(*) comparação (A)InvençãoAll samples were evaluated as described above and the results are summarized in table 4 below.

(*) comparison (A) Invention

The elastomeric compositions 8 to 11 according to the current invention, when compared to the comparison elastomeric composition 7 (set to 100) showed a reduced viscosity in its non-cross-linked state, thus showing a better processing capacity. In addition, elastomeric compositions 8 to 11 showed equal or improved static and dynamic mechanical properties. More especially, elastomeric compositions 8 to 11 showed improved modulus.

In addition, the elastomeric compositions 8 to 11 showed a reduced thermoplastic capacity, indicated by the reduced value of ΔE '(value of ΔE'lower between 10 ° C and 70 ° C).

EXAMPLE 3 Preparation of elastomeric compositions 12 and 13 (side insert)

The elastomeric compositions 12 and 13 shown in table 5 were prepared as follows (the amounts of the various components are shown in ppc).

(*) Comparação (A) InvençãoAll components, except sulfur and accelerators (TBBS), were mixed together in an internal mixer (model Pomini PL 1.6) for about 5 minutes (first stage). As soon as the temperature reached 145 ± 5 ° C, the elastomeric composition was discharged. The sulfur accelerators (TBBS) were then added and mixing was carried out in an open roller mixer (second stage).

(*) Comparison (A) Invention

BR: polybutadiene (Europrene Neocis® BR40-Polimeri Europa);

IR: cis-1,4-polyisoprene (SKI-Nizhnekamskamskneftechim Export);

N660: carbon black;

Silica: Zeosil® 1115 MP (Rhodia);

TESPT: bis (3-triethoxysilylpropyl) tetrasulfide (Degussa-Hüls);

GF001: micronized glass flakes with thickness around 1 pm and aspect ratio around 45: 1 treated with about 8% by weight of TESPD (Glass Flake Ltd.);

Antioxidant: phenyl-p-phenylenediamine (6-PPD-Akso Nobel);

TBBS: N-tert-butyl-2-benzothiazilsulfenamide (Vulkacit®

NZ / EGC-Lanxess).

(*): comparação (A): invençãoAll samples were evaluated as described above and the results were summarized in table 6 below.

(*): comparison (A): invention

The elastomeric composition 13 according to the current invention, when compared to the comparative elastomeric composition 12 (adjusted to 100) showed a reduced viscosity in its non-cross-linked state, thus showing a better processing capacity. In addition, the elastomeric compositions 13 showed equal or improved static and dynamic mechanical properties. More especially, the compositions and elastomers 13 showed an improved modulus, an improved dynamic elastic modulus and reduced thermoplasticity, indicated by the reduced ΔE' value (lower ΔE' value between 23 ° C and 70 ° C).

EXAMPLE 4 Preparation of elastomeric compositions 14 to 16 (bead load)

The elastomeric compositions 14 to 16 shown in table 7 were prepared as follows (the amounts of the various components are shown in ppc).

(*): comparação (A): invençãoAll components, except sulfur, accelerators and methylene donor (TBBS + HMMM), were mixed together in an internal mixer (model Pomini PL 1.6) for about 5 minutes (first stage). As soon as the temperature reached 145 ± 5 ° C, the elastomeric composition was discharged. The sulfur, accelerator and methylene donor were then added, and the mixing was carried out in an open roller mixer (second stage).

(*): comparison (A): invention

IR: cis-1,4-polyisoprene (SKI-Nizhnekamskamskneftechim Export);

N326: carbon black;

GF001: micronized glass flakes with thickness around 1 pm and aspect ratio around 45: 1 treated with about 8% by weight of TESPD (Glass Flake Ltd.);

GF350nm: flakes of ground glass with a thickness of about 350 nm and aspect ratio around 850: 1, treated with about 8% by weight of TESPD;

Antioxidant: phenyl-p-phenylenediamine (6-PPD-Akso Nobel);

TBBS: N-tert-butyl-2-benzothiazilsulfenamide (Vulkacit® NZ / EGC-Lanxess).

HMMM: hexamethoxymethyl melamine.

(*): comparison (A): the invention

The elastomeric compositions 15 and 16 according to the current invention, when compared to the comparison elastomeric composition 14 (adjusted to 100) showed a reduced viscosity in its non-cross-linked state, thus showing a better processing capacity. In addition, elastomeric compositions 15 and 10 16 showed equal or improved static and dynamic mechanical properties. More especially, the elastomeric compositions 15 and 16 showed the improved modulus and the improved dynamic elastic modulus.

Claims (22)

1. A tire comprising at least one structural element, including a crosslinked elastomeric material obtained by crosslinking a crosslinkable elastomeric composition, _ comprising: (a) 100 ppc of at least one elastomeric polymer; (b) about 0.1 ppc to about 120 ppc for at least one reinforcement charge; said crosslinkable elastomeric composition characterized by the fact that it further comprises: (c) about 1 ppc to about 80 ppc of glass flakes having an average thickness equal to or less than 5.0 pm and an average aspect ratio greater than 1 . 2. Tire according to claim 1, characterized in that said tire comprises: - a carcass structure with a substantially toroidal shape, having opposite side edges associated with the right and left bead structures; - a belt structure applied in a radially external position with respect to said carcass structure; - a tread applied in a radially external position with respect to said belt structure; - a pair of sides applied laterally on the opposite sides with respect to said carcass structure; wherein said structural element is at least one of said tread, or said pair of sides. 3. Tire according to claim 2, characterized in that the bead structures are defined by the respective folds of the carcass and are made up of at least one bead core and at least one bead load, said bead load being said structural element. 4. Tire according to claim 2 or 3, characterized in that it additionally comprises: -a tread sublayer applied in a radially internal position with respect to said tread; wherein said structural element is said tread sublayer. Tire according to any of claims 2 to 4, characterized in that said tire comprises: -a pair of side inserts extending radially from each of the said bead structures to the corresponding side edge of said tread ; and wherein said structural element is said pair of side inserts. Tire according to any of claims 2 to 5, characterized in that said tire comprises: -a pair of anti-abrasive layers placed in an axially external position with respect to said carcass fold; wherein said structural element is said pair of anti-abrasive layers. Tire according to one of claims 1 to 6, characterized in that said glass flakes have an average thickness of about 0.01 pm to about 5.0 pm. Tire according to claim 7, characterized in that said glass flakes have an average thickness of about 0.05 pm to about 2.0 pm. Tire according to claim 8, characterized in that said glass flakes have an average thickness of about 0.2 pm to about 1.0 pm. Tire according to any of the preceding claims, characterized in that said glass flakes have an average diameter of about 0.1 pm to about 3000 pm. Tire according to claim 10, characterized in that said glass flakes have an average diameter of about 1 pm to about 1500 pm. Tire according to claim 11, characterized in that said glass flakes have an average diameter of about 1 pm to about 500 pm. 13. Tire according to any of the preceding claims, characterized in that said glass flakes have an average aspect ratio greater than 2. Tire according to claim 13, characterized in that said glass flakes have an aspect ratio greater than 10. 15. Tire according to any of the preceding claims, characterized in that said glass flakes have an average aspect ratio in the range of about 10: 1 to about 1000: 1. 16. Tire according to claim 15, characterized in that said glass flakes have an average aspect ratio in the range of about 20: 1 to about 900: 1. 17. Tire according to claim 16, characterized in that said glass flakes have an average aspect ratio in the range of about 50: 1 to about 800: 1. 18. Tire according to any of the preceding claims, characterized in that said glass flakes are treated on the surface with functional silanes. 19. Tire according to claim 18, characterized in that said functional silane is selected from the group consisting of aminopropyltrialoxysilanes, vinyltrialoxysilanes, glycidoxypropyltrialoxysilanes, methacryloxy-propyltrialoxysilanes, polysulfurized alkoxysilanes, or mixtures thereof. 20. Tire according to any of the preceding claims 5, characterized in that the projected area of said glass flakes represents at least 50% of the total projected area of all glass particles. 21. Tire according to any of the preceding claims, characterized in that the amount of said glass flakes 10 varies from about 2 ppc to about 60 ppc. 22. Tire according to claim 21, characterized in that the amount of said glass flakes varies from about 3 ppc to about 20 ppc.

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